1. Field of Invention
This invention relates to hand tools and is particularly directed to socket wrenches which are adjustable to accommodate bolts of a plurality of sizes.
2. Prior Art
For many years, wrenches have been extremely useful tools for tightening and loosening nuts, bolts and the like. More recently, adjustable wrenches have found wide acceptance, since they are readily adaptable to accommodate nuts and bolts of a wide variety of sizes. Still more recently, socket wrenches have gained wide acceptance. Socket wrenches are tubular members having a driving end of generally hexagonal configuration, sized to fit a nut or bolt of a given size and having the opposite end formed to receive a drive mechanism, which may be either manual or powered. The advantage of the socket wrenches is that they be driven by power sources, as well as manually. However, the socket wrenches of the prior art have not been adjustable. Hence, it has been necessary to purchase sets of socket wrenches to accommodate most standard sizes of nuts and bolts. Unfortunately, American products are generally made using nuts and bolts of American dimensions, whereas products from most of the rest of the world employ nuts and bolts of metric dimensions. Thus, separate sets of socket wrenches have been required to fit nuts and bolts of each dimension system. Furthermore, it is customary to provide socket wrench sets for only limited ranges of sizes. Thus, for example, one set of socket wrenches would accommodate nuts and bolts having heads of less than one inch diameter, while a separate set of socket wrenches would be required to accommodate nuts and bolts having heads of one to two inch diameter and larger sizes of socket wrenches are usually sold separately.
Numerous attempts have been made heretofore to provide adjustable socket wrenches. However, some of the prior art adjustable socket wrenches have been extremely expensive to produce and have been complicated or difficult to use. Other prior adjustable socket wrenches have been unable to withstand the torque required for normal usage of such devices. Still other prior art adjustable socket wrenches have failed to provide adequate gripping action over more than a very limited range of diameters. A search in the United States Patent Office has revealed the following references:
______________________________________ U.S. Pat. No. INVENTOR ISSUED ______________________________________ 2,631,485 D. O. Stuart et al Mar. 17, 1953 3,373,639 L. Van Dalen et al Mar. 19, 1958 3,898,897 T. U. Jauhainen Aug. 12, 1975 4,385,534 C. R. Nichols May 31, 1983 ______________________________________
Each of these reference teaches a set of arms with essentially a nut which can be tightened to cause the arms to clamp a desired object. The patent to Stuart et al teaches an extremely complex structure which would be very expensive to produce. The remaining patents each have gripping arms which generally engage the article to be clampled at a slight angle and, hence, would tend to slide off of the article. Thus, none of the prior art adjustable socket wrenches have been entirely satisfactory.